Various types of underwater viewing craft have been used or proposed for recreational purposes. Australian patent no. 554,889 discloses a craft which has a lower underwater observation compartment which remains submerged when the craft is ballasted for normal operation. The craft suffers the disadvantage that it has a large displacement and, as a consequence, cannot travel at high speeds. This means that the craft cannot conveniently travel a large distance to a location where underwater observation is desired.
Australian patent no. 569,919 discloses a submersible craft which includes three hulls which are interconnected by lever systems. One of the hulls is submersible with respect to the other two, with articulation of the lever systems, when the craft has reached a location at which an underwater observation is desired to be made. Thus, displacement related problems do not arise. However, a difficulty with the craft which is disclosed in patent no. 569,919 is that passengers are at all time accommodated in the confined space of the submersible hull. There is no access between the main, submersible, hull and the interconnected secondary hulls and it is thought that this could give rise to problems if the craft were required to travel long distances.
The present invention seeks to avoid the above discussed problems by providing a craft having a floating portion which is arranged to carry passengers in the manner of conventional water craft and which also carries a cabin which can be moved into a submerged position as and when required.